Want smarter kids? Genetic diversity could be key

Greater genetic diversity is linked to an increase in height and enhanced cognitive function, a new study finds. The research, involving more than 350,000 people worldwide, also revealed information about the apparent lack of a genetic link related to certain health problems.

It has long been known that children born to more genetically similar parents can have an increased risk of certain disorders caused by inherited genetic mutations, but CBS News medical contributor Dr. David Agus said this study is surprising because it revealed that genetic diversity had no effect on health conditions like diabetes and heart disease.

"If you think about it, evolution...selects out for who has better children and for who does functions that were necessary over the last million years," Agus said Thursday on "CBS This Morning." That would have offered an advantage to early humans, since being taller "means you can run quickly and get away from prey," and higher cognitive function would have helped hunters find their way home.

A team from the University of Edinburgh examined 16 health-related traits sourced from over 100 studies. They analyzed data from over 350,000 people from urban and rural communities and reported their findings in the medical journal Nature.

"Our research answers questions first posed by Darwin as to the benefits of genetic diversity," the study's co-author Dr. Peter Joshi said.

The scientists compiled the mass of genetic data to study people's "homozygosity," having identical copies of a single gene, inherited from their parents.

After separating the information into two groups -- those whose parents had similar versus dissimilar genetic makeups -- they noted that children born from genetically similar parents were shorter by 1.2 cm, on average, and had 10 months less formal education. Researchers also found differences in lung function.

The study is interesting, says Agus, because the last century makes up the first 100 years that society is seeing widespread mixed marriages. And the rate continues to increase.

In 2013, 12 percent of new marriages in the U.S. were between spouses of different races, a number that's been climbing steadily, according to the Pew Research Center.

"This is really the first couple generations where people of different backgrounds are having children, and if this happens in one generation...think of it if it continues to happen," Agus said.